Stamps and methods of forming a pattern on a substrate

ABSTRACT

Methods for fabricating stamps and systems for patterning a substrate, and devices resulting from those methods are provided.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.12/026,214, filed Feb. 5, 2008, now U.S. Pat. No. 8,999,492, issued Apr.7, 2015, the disclosure of which is hereby incorporated herein in itsentirety by this reference.

TECHNICAL FIELD

Embodiments of the invention relate to methods, a stamp and a system forpatterning a substrate by use of self-assembling block copolymers, anddevices resulting from those methods.

BACKGROUND OF THE INVENTION

Lithography is a key process in the fabrication of semiconductorintegrated circuits. Photolithography typically involves projecting animage through a reticle or mask onto a thin film of photoresist or othermaterial that covers a semiconductor wafer or other substrate, anddeveloping the film to remove exposed or unexposed portions of theresist to produce a pattern in subsequent processing steps. Insemiconductor processing, the continual shrinking in feature sizes andthe increasing development of nanoscale mechanical, electrical, chemicaland biological devices requires systems to produce nanoscale features.However, with conventional photolithography using light, the minimumfeature size and spacing between patterns is generally on the order ofthe wavelength of the radiation used to expose the film. This limits theability to produce sub-lithographic features of about 60 nm usingconventional lithography.

Microcontact printing has been developed to create sublithographicfeatures in semiconductor devices. This technique generally involvesstamping or pressing a soft template or stamp bearing small scaletopographic features onto a receptor substrate to form a pattern on thesubstrate. The features on the template are typically prepared byphotolithography or electron (e-beam) lithography. For example, FIG. 1illustrates a conventional soft template or stamp 10 formed, forexample, from polydimethylsiloxane, with defined features 12 structuredwith a stamping surface 14 and sidewalls 16. The stamping surface 14defines a dimension (d) of the pattern to be stamped onto a substrate.As shown in FIG. 2, the features 12 of the stamp are wetted with an ink18 that is physisorbed or chemisorbed onto the stamping surface 14 andthe sidewalls 16 of the features 12. As depicted in FIG. 3, the inkedstamp 10 is brought into contact with a receptor substrate 20 (e.g.,silicon wafer) and the ink 18 is transferred to regions of the substrate20 where the ink 18 forms self-assembled monolayers (SAMs) 22 (FIG. 4).

However, resolution of small features is problematic because ofinconsistent printing due to capillary forces that pull ink 18 sorbed tosurfaces of the features 12 adjacent to the stamping surface 14 (e.g.,the sidewalls 16) onto the substrate 20 (e.g., areas 24). Such wickingof the ink 18 material onto the substrate 20 also alters the intendeddimension (d) of the stamped features (SAMs) 22, as defined by thestamping surfaces 14 of the stamp/template. In addition, the size anddimension of the stamped features 22 on the receptor substrate 20 arelimited to the dimensions (d) of the lithographically formed features 12defined on the stamp.

Other processes such as e-beam lithography and extreme ultraviolet (EUV)lithography have been used in attempts to form sub-lithographicfeatures. However, the high costs associated with such lithographictools have hindered their use.

Self-assembled block copolymer films have been prepared by patterningthe surface of a substrate with chemical stripes (chemical templating),each stripe being preferentially wetted by the alternate blocks of ablock copolymer. A block copolymer film with lamellar morphology, aperiodicity matching the stripe pattern and both blocks being neutralwetting at the air interface (e.g., PS-PMMA) that is cast on thepatterned substrate and thermally annealed will self-assemble so thatthe domains orient themselves above the preferred stripes andperpendicular to the surface. However, the process has no advantage overEUV lithography or other sub-lithographic patterning techniques sinceone of these patterning techniques must be used to form the substratetemplate pattern, and with the use of expensive patterning tools, thelow-cost benefits of using block copolymers are lost.

It would be useful to provide a method and system for preparingsub-lithographic features that overcome existing problems.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are described below with reference to thefollowing accompanying drawings, which are for illustrative purposesonly. Throughout the following views, the reference numerals will beused in the drawings, and the same reference numerals will be usedthroughout the several views and in the description to indicate same orlike parts.

FIG. 1 illustrates an elevational, cross-sectional view of aconventional stamp used in a microcontact printing application.

FIG. 2 illustrates a diagrammatic view of the stamp of FIG. 1, with inkphysisorbed or chemisorbed onto the surface of the stamp, and a receptorsubstrate to be contacted by the inked stamp.

FIG. 3 illustrates the inked stamp of FIG. 2, brought into contact withthe receptor substrate, according to a conventional microcontactprinting process.

FIG. 4 illustrates a subsequent processing step with the formation ofSAMs from the transferred ink on the receptor substrate.

FIG. 5 illustrates a diagrammatic top plan view of a portion of asubstrate of a stamp at a preliminary processing stage according to anembodiment of the present disclosure, showing the substrate withtrenches. FIGS. 5A and 5B are elevational, cross-sectional views of thesubstrate depicted in FIG. 5 taken along lines 5A-5A and 5B-5B,respectively.

FIG. 6 is a top plan view of a portion of a substrate according toanother embodiment showing the substrate with trenches for forming astamp with a hexagonal close-packed array of perpendicular cylinders.

FIGS. 7 and 8 illustrate diagrammatic top plan views of the stamp ofFIG. 5 at various stages of the fabrication of a self-assembled blockcopolymer film according to an embodiment of the present disclosure.FIGS. 7A-8A illustrate elevational, cross-sectional views of embodimentsof a portion of the substrate depicted in FIGS. 7 and 8 taken,respectively, along lines 7A-7A and lines 8A-8A. FIG. 7B is across-sectional view of the substrate depicted in FIG. 7 taken alonglines 7B-7B.

FIG. 9 is a top plan view of the stamp of FIG. 6 at a subsequent stageof fabrication showing a self-assembled polymer film composed of ahexagonal array of cylinders within the trenches.

FIG. 10 is a top plan view of the stamp of FIG. 5 at a subsequent stageof fabrication according to another embodiment of the invention, showinga self-assembled polymer film composed of a single row of cylinders withthe trenches. FIG. 10A is a cross-sectional view of the substratedepicted in FIG. 10 taken along lines 10A-10A.

FIG. 11 is a top plan view of the stamp of FIG. 5 at a subsequent stageof fabrication according to another embodiment of the invention, showinga self-assembled polymer film composed of a parallel row ofhalf-cylinders with the trenches. FIG. 11A is a cross-sectional view ofthe substrate depicted in FIG. 10 taken along lines 11A-11A.

FIG. 12 illustrates a diagrammatic top plan view of a portion of a stampat a preliminary processing stage according to another embodiment of thedisclosure, showing a chemically differentiated stamping surface. FIG.12A is an elevational, cross-sectional view of the substrate depicted inFIG. 12 taken along lines 12A-12A.

FIGS. 13 and 14 illustrate diagrammatic top plan views of the stamp ofFIG. 12 at subsequent processing stages. FIGS. 13A and 14A illustrateelevational, cross-sectional views of a portion of the substratedepicted in FIGS. 13 and 14 taken, respectively, along lines 13A-13A andlines 14A-14A. FIGS. 13B and 14B are cross-sectional views of thesubstrate of FIGS. 13-14 taken, respectively, along lines 13B-13B andlines 14B-14B.

FIGS. 15-18 illustrate subsequent steps in the use of the stamp of FIGS.8 and 8A in a contact printing process to form a pattern on a substrateaccording to an embodiment of the invention. FIG. 18A is across-sectional view of the substrate shown in FIG. 18, taken alonglines 18A-18A.

FIGS. 19 and 20 illustrate an embodiment of the use of a chemicallydifferentiated surface of the substrate shown in FIG. 18A for theselective deposit and formation of a self-assembled block copolymerfilm, shown in a cross-sectional view.

FIGS. 21 and 22 illustrate the use of the self-assembled block copolymerfilm of FIG. 20 after removal of one of the polymer blocks, as a mask toetch the substrate and filling of the etched opening.

FIG. 23 illustrates another embodiment of the use of the stamped patternof an ink material shown in FIG. 18A to guide deposition of a materialonto exposed portions of the substrate to form a chemicallydifferentiated surface, shown in a cross-sectional view.

FIG. 24 illustrates the use of the deposited material of the structureshown in FIG. 23 as a mask to etch the underlying substrate.

FIG. 25 illustrates yet another embodiment of the use of the stampedpattern of an ink material shown in FIG. 18A as a seed material forselective deposition of an additional material to increase the thicknessand/or hardness of the ink elements on the substrate, shown in across-sectional view.

FIG. 26 illustrates the use of the ink pattern with added material shownin FIG. 25 as a mask to etch openings in the underlying substrate.

FIGS. 27-32 illustrate steps in another embodiment of a method accordingto the invention to chemically pattern a substrate, shown in across-sectional view. FIGS. 31 and 32 illustrate the removal ofnon-crosslinked polymer material and the use of the inked pattern todirect self-assembly of a block copolymer material.

FIG. 33 illustrates an elevational, cross-sectional view of anembodiment of a substrate bearing a neutral wetting layer at apreliminary processing step.

FIG. 34 illustrates the substrate of FIG. 33 at a subsequent processingstep.

FIGS. 35-39 illustrate an embodiment of a process according to theinvention for forming a chemically patterned master template for forminga stamp for use in inducing self-assembly of a lamellar-phase blockcopolymer material on a substrate. FIG. 35 illustrates a perspectiveview of a base substrate at a preliminary processing stage bearing ahydrophilic material on the surface. FIGS. 36-39 illustrate thesubstrate of FIG. 35 at subsequent processing stages to form a patternedmaster template. FIGS. 37A, 38A, and 39A illustrate top plan views andFIGS. 37B, 38B, and 39B illustrate elevational, cross-sectional views ofthe substrates shown in FIGS. 37, 38, and 39, respectively.

FIGS. 40-43 illustrate another embodiment of a process for forming achemically patterned master template for use in forming a stamp fordirecting self-assembly of a lamellar-phase block copolymer material.FIG. 40 illustrates a perspective view of a base substrate at apreliminary processing stage bearing a hydrophobic material on thesurface. FIGS. 41-43 illustrate the substrate of FIG. 40 at subsequentprocessing stages to form a patterned master template. FIGS. 41A, 42A,and 43A illustrate top plan views and FIGS. 41B, 42B, and 43B illustrateelevational, cross-sectional views of the substrates shown in FIGS. 41,42, and 43, respectively.

FIGS. 44-47 illustrate an embodiment according to the invention forforming a stamp on a master template as illustrated in FIG. 39. FIG. 44illustrates a perspective view of a master template with a material forforming the stamp in a preliminary processing stage. FIG. 45 illustratesthe master template/stamp material complex at a subsequent processingstep. FIGS. 44A and 45A illustrate top plan views and FIGS. 44B and 45Billustrate elevational, cross-sectional views of the mastertemplate/stamp material complex shown in FIGS. 44 and 45, respectively.FIGS. 46 and 47 illustrate elevational, cross-sectional views of themaster template/stamp material complex of FIG. 45 at subsequentprocessing steps showing the removal of the chemically patterned stampfrom the master template. FIG. 47A illustrates a perspective view of thestamp of FIG. 47, showing the chemically patterned surface of the stamp.

FIGS. 48-52 illustrate an embodiment of the invention for using thestamp illustrated in FIGS. 47 and 47A for directing ordering of alamellar-phase block copolymer material. FIGS. 48 and 49 illustrateelevational, cross-sectional views of the stamp brought into contactwith the block copolymer material on a substrate. FIG. 50 illustrates anelevational, cross-sectional view of the annealing of the blockcopolymer material in contact with the stamp. FIG. 50A illustrates a topplan view of the surface of the annealed block copolymer material ofFIG. 50. FIGS. 51 and 52 illustrate the removal of the chemicallypatterned stamp from the annealed and self-assembled block copolymermaterial of FIG. 50, shown in an elevational, cross-sectional view.

FIGS. 53-55 illustrate the use of the self-assembled lamellar-phaseblock copolymer material of FIG. 52 to mask and etch an underlyingsubstrate. FIG. 53 illustrates an elevational, cross-sectional view ofthe block copolymer material of FIG. 52 at a subsequent processing stepto selectively remove polymer domains to form a mask with openings tothe substrate. FIGS. 54 and 55 illustrate the substrate shown in FIG. 53at subsequent processing stages to form and fill openings in thesubstrate. FIGS. 53A, 54A, and 55A are top plan views of the substrateshown in FIGS. 53, 54, and 55, respectively.

FIGS. 56-58 illustrate another embodiment of a process for forming achemically patterned master template and stamp for directingself-assembly of a cylinder-phase block copolymer material. FIG. 56illustrates a perspective view of a master template having a surfacebearing dots composed of a hydrophilic material amidst a hydrophobicmaterial. FIG. 56A is a top plan view and FIG. 56B is an elevational,cross-sectional view of the master template shown in FIG. 56.

FIG. 57 illustrates an embodiment of a stamp formed from the mastertemplate of FIG. 56 in an elevational, cross-sectional view. FIG. 57A isa top plan view of the surface of the stamp of FIG. 57.

FIG. 58 illustrates an embodiment of the use of the stamp of FIG. 57 todirect ordering of a cylindrical-phase block copolymer material in anelevational, cross-sectional view. FIG. 58A illustrates a top plan viewof the surface of the annealed and ordered block copolymer material ofFIG. 58.

FIG. 59 illustrates an elevational, cross-sectional view of the use ofthe self-assembled cylindrical-phase block copolymer material of FIGS.58 and 58A to mask and etch an underlying substrate.

FIG. 60 illustrates the substrate shown in FIG. 59 at a subsequentprocessing stage to fill the cylindrical openings in the substrate. FIG.60A is a top plan view of the substrate shown in FIG. 60.

FIG. 61 illustrates geometries for an integrated circuit layout that canbe prepared using embodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The following description with reference to the drawings providesillustrative examples of devices and methods according to embodiments ofthe invention. Such description is for illustrative purposes only andnot for purposes of limiting the same.

In the context of the current application, the term “semiconductorsubstrate” or “semiconductive substrate” or “semiconductive waferfragment” or “wafer fragment” or “wafer” will be understood to mean anyconstruction comprising semiconductor material, including, but notlimited to, bulk semiconductive materials such as a semiconductor wafer(either alone or in assemblies comprising other materials thereon), andsemiconductive material layers (either alone or in assemblies comprisingother materials). The term “substrate” refers to any supportingstructure, including, but not limited to, the semiconductive substrates,wafer fragments or wafers described above.

“L_(o)” is the inherent periodicity or pitch value (bulk period orrepeat unit) of structures that self-assemble upon annealing from aself-assembling (SA) block copolymer or a blend of a block copolymerwith one or more of its constituent homopolymers.

The term “chemical affinity” means the tendency of molecules toassociate with each other based upon chemical forces between themolecules. The term “physiosorbed” means the physical adsorption of amolecule (e.g., ink material) to a surface, for example, through weakintermolecular interactions such as Van der Waals forces. The term“chemisorbed” means the chemical adsorption of a molecule (e.g., inkmaterial) to a surface, for example, through chemically bonding such asthrough hydrogen bonds, ionic bonds, dithiol linkages, electrostaticbonds or other “weak” chemical bond.

In embodiments of the invention, a stamp or template is prepared byguided self-assembly of block copolymers, with both polymer domains atthe air interface. Block copolymer films spontaneously assemble intoperiodic structures by microphase separation of the constituent polymerblocks after annealing, forming ordered domains at nanometer-scaledimensions. One of the polymer blocks has affinity for and is swelled byabsorption of an ink chemical and a second polymer domain hassubstantially no affinity for the ink chemical and remains unchanged.The chemical ink can then be transferred from the stamp to a receptorsubstrate where the ink forms SAMs. The resolution of the imprinted SAMsexceed other microcontact techniques using self-assembled polymer films,and processing costs using the technique is significantly less thanusing electron beam lithography or EUV photolithography, which havecomparable resolution.

The two-dimensional (2D) inked pattern that is formed on the receptorsubstrate can then be used, for example, as a template or pattern forself-assembled ordering of a block copolymer film that is cast onto thepatterned receptor substrate. Following self-assembly on the receptorsubstrate, one block of the copolymer can then be selectively removedand the remaining patterned film used as an etch mask for patterningnanosized features into the underlying substrate.

Methods for fabricating a stamp composed of a self-assembled blockcopolymer thin film that defines nanometer-scale cylindrical and lineararray patterns according to embodiments of the invention are illustratedin FIGS. 5-14B.

In some embodiments, the stamp is prepared under processing conditionsthat use a graphoepitaxy technique utilizing the sidewalls of trenchesas constraints to induce orientation and registration of a film of aself-assembling diblock copolymer to form an ordered array patternregistered to the trench sidewalls. Graphoepitaxial techniques can beused to order cylindrical-phase diblock copolymers in one dimension, forexample, parallel lines of half-cylinders, hexagonal close-packed arraysof perpendicular cylinders, or a single row of perpendicular cylinderswithin lithographically defined trenches. A desired pattern of cylinderson the stamp can be prepared by providing trenches having walls that areselective to one polymer block of a block copolymer and a floor composedeither of a material that is block-sensitive or preferentially wettingto one of the blocks of the block copolymer in trenches where lines ofparallel half-cylinders are desired, or a material that is neutralwetting to both blocks in trenches where an array of perpendicularcylinders are desired.

Additionally, in some embodiments, the trench floors can be chemicallydifferentiated to provide a wetting pattern to control orientation ofthe microphase separated and self-assembling cylindrical domains in asecond dimension, for example, parallel lines of half-cylinders orperpendicular-oriented cylinders. The trench floors are structured orcomposed of surface materials to provide a neutral wetting surface orpreferential wetting surface to impose ordering on a block copolymerfilm that is then cast on top of the substrate and annealed to producedesired arrays of nanoscaled lines and/or cylinders.

As illustrated in FIGS. 5-5B, a base substrate 28 is provided, which canbe silicon, silicon oxide, silicon nitride, silicon oxynitride, siliconoxycarbide, among other materials. In some embodiments, a neutralwetting material 30 is formed over the base substrate 28. A materiallayer 32 to be etched can then be formed over the neutral wettingmaterial 30 and etched to form trenches 34. Portions of the materiallayer 32 form a spacer 36 between the trenches 34. The trenches 34 arestructured with opposing sidewalls 38, opposing ends 40, a floor 42, awidth (w_(t)), a length (l_(t)) and a depth (D_(t)).

As illustrated in FIG. 6, in embodiments for forming a stamp 26′ with ahexagonal close-packed array of perpendicular cylinders, ends 40′ oftrenches 34′ are angled to sidewalls 38′, for example, at an about 60°angle, and in some embodiments, the trench ends are slightly rounded. Inother embodiments, the material layer 32 can be formed on the basesubstrate 28, etched to form the trenches 34, and then a neutral wettingmaterial (e.g., random copolymer) 30 can be applied to the trench floors42 and crosslinked. Non-crosslinked random copolymer material outsidethe trenches 34 (e.g., on the spacers 36) can be subsequently removed.

The trenches can be formed using a lithographic tool having an exposuresystem capable of patterning at the scale of L_(o) (10-100 nm). Suchexposure systems include, for example, extreme ultraviolet (EUV)lithography, proximity X-rays and electron beam (e-beam) lithography, asknown and used in the art. Conventional photolithography can attain (atsmallest) about 58 nm features.

A method called “pitch doubling” or “pitch multiplication” can also beused for extending the capabilities of photolithographic techniquesbeyond their minimum pitch, as described, for example, in U.S. Pat. No.5,328,810 (Lowrey et al.), U.S. Pat. No. 7,115,525 (Abatchev et al.), US2006/0281266 (Wells), now U.S. Pat. No. 7,396,781, issued Jul. 8, 2008,and US 2007/0023805 (Wells), now U.S. Pat. No. 7,776,715, issued Aug.17, 2010. Briefly, a pattern of lines is photolithographically formed ina photoresist material overlying a layer of an expendable material,which in turn overlies a substrate, the expendable material layer isetched to form placeholders or mandrels, the photoresist is stripped,spacers are formed on the sides of the mandrels, and the mandrels arethen removed, leaving behind the spacers as a mask for patterning thesubstrate. Thus, where the initial photolithography formed a patterndefining one feature and one space, the same width now defines twofeatures and two spaces, with the spaces defined by the spacers. As aresult, the smallest feature size possible with a photolithographictechnique is effectively decreased down to about 30 nm or less.

The boundary conditions of the trench sidewalls 38 in both the x- andy-axis impose a structure wherein each trench contains “n” number offeatures (e.g., cylinders, lamellae, etc.). Factors in forming a singlearray or layer of nanostructures within the trenches include the widthand depth of the trench, the formulation of the block copolymer toachieve the desired pitch (L_(o)), and the thickness (t) of thecopolymer film. The length (l) of the trenches is at or about nL_(o)where n is an integer multiple of L_(o), typically within a range ofabout n*10-n*100 nm (with n being the number of features or structures(i.e., cylinders)). The depth (D_(t)) of the trenches 34 is about equalto L_(o) (D_(t)˜L₀) such that a cast block copolymer material 44 ofabout L_(o) will fill the trenches, and is generally over a range ofabout 10-100 nm. The trenches 34 are constructed with a width (w_(t))such that a block copolymer (or blend) will self-assemble upon annealinginto a single layer of n elements (e.g., cylinders, lamellae, etc.)spanning the width (w_(t)) of the trench, with the center-to-centerdistance of adjacent identical elements being at or about L_(o). Thewidth of the spacer 36 between adjacent trenches can vary and isgenerally about L_(o) to about nL_(o). In some embodiments, the trenchdimension is about 100-1,500 nm wide (w_(t)) and about 100-25,000 nm inlength (l_(t)), with a depth (D_(t)) of about 10-100 nm.

To form a single layer of n lamellae from a lamellar-phase blockcopolymer (inherent pitch value of L_(o)), which spans the widthregistered to the sidewalls 38 for the length of the trench 34, thewidth (w_(t)) of the trenches can be a multiple of the inherent pitchvalue (L_(o)) of the polymer, being equal to or about nL_(o) (“n*L_(o)”)and typically ranging from about n*10 to about n*100 nm (with n beingthe number of features or structures). For forming a 1D array ofperpendicular-oriented cylinders with a center-to-center pitch of at orabout L_(o) (e.g., a width of about 65-75 nm for an L_(o) value of about36-42 nm), the trenches 34 can be constructed with a width (w_(t)) ofabout 2*L_(o) or less, e.g., about 1.0*L_(o) to about 2*L_(o) (e.g.,about 1.75*L_(o)). For forming parallel lines of half-cylinders or aperiodic, hexagonal close-pack or honeycomb array of perpendicularcylinders, the trenches 34, 34′ can be constructed with a width (w_(t))at or about an integer multiple of the L_(o) value or nL_(o) where n=3,4, 5, etc. (e.g., a width of about 120-2,000 nm for an L_(o) value ofabout 36-42 nm).

For example, a block copolymer having a 35 nm pitch (L_(o) value)deposited into a 75 nm wide trench having a neutral wetting floor will,upon annealing, result in a zigzag pattern of 35 nm diameterperpendicular cylinders that are offset by a half distance for thelength (l_(b)) of the trench, rather than a single line of perpendicularcylinders aligned with the sidewalls down the center of the trench. Asthe L_(o) value of the copolymer is increased, for example, by forming aternary blend by the addition of both constituent homopolymers, there isa shift from two rows to one row of the perpendicular cylinders withinthe center of the trench.

A block copolymer material of about L_(o) is deposited to about fill thetrenches 34 and, upon annealing, the block copolymer film willself-assemble into morphologies to foim an array of elements that areoriented in response to the wetting properties of the trench surfaces.Entropic forces drive the wetting of a neutral wetting surface by bothblocks, and enthalpic forces drive the wetting of a preferential-wettingsurface by the preferred block (e.g., the minority block). The trenchsidewalls 38 and ends 40 are structured to be preferential wetting byone block of the block copolymer to induce registration of elements(e.g., cylinders, half-cylinders, lamellae, etc.) as the polymer blocksself-assemble. Upon annealing, the preferred block of the blockcopolymer will segregate to the sidewalls and edges of the trench toassemble into a thin (e.g., ¼ pitch) interface (wetting) layer, and willself-assemble to form elements according to the wetting surface of thetrench floor 42.

For example, in response to neutral wetting properties of the trenchfloor surface material (e.g., crosslinked neutral wetting randomcopolymer mat) and preferential wetting sidewalls and ends, an annealedcylinder-phase block copolymer film will self-assemble to form cylindersin a perpendicular orientation to the trench floors in the center of apolymer matrix, and a lamellar-phase block copolymer film willself-assemble into a lamellar array of alternating polymer-rich blocks(e.g., PS and PMMA) that extend across the width and for the length ofthe trench and are oriented perpendicular to the trench floor andparallel to the sidewalls. In a trench having a preferential wettingfloor, sidewalls and ends, an annealed cylinder-phase block copolymerfilm will self-assemble to form lines of half-cylinders in a polymermatrix extending the length of the trench and parallel to the trenchfloor.

The structuring of the trench sidewalls 38 and ends 40 to bepreferential wetting causes one of the blocks of the copolymer materialto form a thin wetting layer on those surfaces. To provide preferentialwetting surfaces, for example, in the use of a PS-b-PMMA blockcopolymer, the material layer 32 can be composed of silicon (with nativeoxide), oxide (e.g., silicon oxide, SiO_(x)), silicon nitride, siliconoxycarbide, indium tin oxide (ITO), silicon oxynitride, and resistmaterials such as methacrylate-based resists, among other materials,which exhibit preferential wetting toward the PMMA block. In the use ofa cylinder-phase copolymer material, the material will self-assemble toform a thin (e.g., ¼ pitch) interface layer of PMMA and PMMA cylindersor half-cylinders (e.g., ½ pitch) in a PS matrix. In the use of alamellar-phase block copolymer material, the material will assemble intoalternating PMMA and PS lamellae (e.g., ½ pitch) within each trench,with PMMA at the sidewall interface (e.g., ¼ pitch).

In other embodiments, a preferential wetting material such as apolymethylmethacrylate (PMMA) polymer modified with an —OH containingmoiety (e.g., hydroxyethylmethacrylate) can be applied onto the surfacesof the trenches 34, for example, by spin coating and then heating (e.g.,to about 170° C.) to allow the terminal OH groups to end-graft to oxidesidewalls 38 and ends 40 of the trenches 34. Non-grafted material can beremoved by rinsing with an appropriate solvent (e.g., toluene). See, forexample, Mansky et al., Science, 1997, 275, 1458-1460, and In et al.,Langmuir, 2006, 22, 7855-7860.

The structuring of the trench floors 42 to be neutral wetting (equalaffinity for both blocks of the copolymer) allows both blocks of thecopolymer material to wet the floor of the trench. A neutral wettingmaterial 30 can be provided by applying a neutral wetting polymer (e.g.,a neutral wetting random copolymer) onto the base substrate 28, formingthe material layer 32 and then etching the trenches to expose theunderlying neutral wetting material, as illustrated in FIGS. 5-5B. Aneutral wetting random copolymer can also be applied after forming thetrenches, for example, as a blanket coat by casting or spin-coating intothe trenches and thermally processing to flow the material into thebottom of the trenches by capillary action, which results in a layer(mat) composed of the crosslinked, neutral wetting random copolymer. Inanother embodiment, the random copolymer material within the trenchescan be photo-exposed (e.g., through a mask or reticle) to crosslink therandom copolymer within the trenches to form the neutral wettingmaterial layer. Non-crosslinked random copolymer material outside thetrenches (e.g., on the spacers 36) can be subsequently removed.

For example, in the use of a poly(styrene-block-methyl methacrylate)block copolymer (PS-b-PMMA), a thin film of a photo-crosslinkable randomPS:PMMA copolymer (PS-r-PMMA) which exhibits non-preferential or neutralwetting toward PS and PMMA can be cast onto the base substrate 28 (e.g.,by spin coating). The polymer material can be fixed in place by grafting(on an oxide substrate) or by thermally or photolytically crosslinking(any surface) to form a mat that is neutral wetting to PS and PMMA andinsoluble due to the crosslinking.

In another embodiment, a neutral wetting random copolymer of polystyrene(PS), polymethacrylate (PMMA) with hydroxyl group(s) (e.g.,2-hydroxyethyl methacrylate (P(S-r-MMA-r-HEMA)) (e.g., about 58% PS) canbe can be selectively grafted to a base substrate 28 (e.g., an oxide) asa layer 30 about 5-10 nm thick by heating at about 160° C. for about 48hours. See, for example, In et al., Langmuir, 2006, 22, 7855-7860.

A surface that is neutral wetting to PS-b-PMMA can also be prepared byspin coating a blanket layer of a photo- or thermally crosslinkablerandom copolymer such as a benzocyclobutene- orazidomethylstyrene-functionalized random copolymer of styrene and methylmethacrylate (e.g., poly(styrene-r-benzocyclobutene-r-methylmethacrylate (PS-r-PMMA-r-BCB)). For example, such a random copolymercan comprise about 42% PMMA, about (58-x) % PS and x % (e.g., about2-3%) of either polybenzocyclobutene or poly(para-azidomethylstyrene)).An azidomethylstyrene-functionalized random copolymer can be UVphoto-crosslinked (e.g., 1-5 MW/cm^2 exposure for about 15 seconds toabout 30 minutes) or thermally crosslinked (e.g., at about 170° C. forabout 4 hours) to form a crosslinked polymer mat as a neutral wettinglayer 30. A benzocyclobutene-functionalized random copolymer can bethermally crosslinked (e.g., at about 200° C. for about 4 hours or atabout 250° C. for about 10 minutes).

In another embodiment in which the base substrate 28 is silicon (withnative oxide), another neutral wetting surface for PS-b-PMMA can beprovided by hydrogen-terminated silicon. For example, the floors 42 oftrenches 34 can be etched, for example, with a hydrogen plasma, toremove the oxide material and form hydrogen-terminated silicon 30, whichis neutral wetting with equal affinity for both blocks of a blockcopolymer material such as PS-b-PMMA. H-terminated silicon can beprepared by a conventional process, for example, by a fluoride ion etchof a silicon substrate (with native oxide present, about 12-15 Å) byexposure to an aqueous solution of hydrogen fluoride (HF) and bufferedHF or ammonium fluoride (NH₄F), by HF vapor treatment, or by a hydrogenplasma treatment (e.g., atomic hydrogen). An H-terminated siliconsubstrate can be further processed by grafting a random copolymer suchas PS-r-PMMA selectively onto the substrate resulting in a neutralwetting surface, for example, by an in situ free radical polymerizationof styrene and methyl methacrylate using a di-olefinic linker such asdivinylbenzene which links the polymer to the surface to produce anabout 10-15 nm thick film.

In other embodiments, to induce formation of parallel half-cylinders inthe trenches, the trenches are structured with a floor surface that ispreferential wetting by one of the polymer blocks of a block copolymer.Annealing of a cylindrical-phase block copolymer material having aninherent pitch value of about L_(o) will result in “n” rows or lines ofhalf-cylinders (parallel to the sidewalls and trench floor) extendingthe length (l_(t)) and spanning the width (w_(t)) of the trenches.

Preferential wetting floors 42 can be provided by a silicon materialwith an overlying layer 30 of native oxide, or by forming a layer 30 ofoxide (e.g., silicon oxide, SiO_(x)), silicon nitride, siliconoxycarbide, ITO, silicon oxynitride, resist material such asmethacrylate-based resists, etc., over the base substrate 28.

Referring now to FIGS. 7-7B, a film of a self-assembling block copolymermaterial 44 having an inherent pitch at or about L_(o) (or a ternaryblend of block copolymer and homopolymers blended to have a pitch at orabout L_(o)) is then deposited into the trenches 34 and onto the trenchfloors 42, and processed such that the copolymer material 44 will thenself-assemble. The block copolymer material 44 can be deposited by spincasting or spin-coating from a dilute solution (e.g., about 0.25-2 wt %solution) of the copolymer in an organic solvent such as dichloroethane(CH₂Cl₂) or toluene, for example.

Capillary forces pull excess of the block copolymer material 44 (e.g.,greater than a monolayer) into the trenches 34. In a trench having adepth (D_(t)) at or about the L_(o) value of the copolymer material 44,the block copolymer is deposited to fill the trench 34 such that thefilm thickness (t₁) of the deposited block copolymer 44 is generally ator about L_(o) and the film will self-assemble to form a single layer ofelements (e.g., cylinders, lamellae, etc.) across the width (w_(t)) ofthe trench, the elements having a diameter/width at or about 0.5 L_(o)(e.g., about 20 nm). For example, a typical thickness (t₁) of alamellar-phase PS-b-PMMA block copolymer film 44 is about ±20% of theL_(o) value of the copolymer (e.g., about 10-100 nm) to form alternatingpolymer-rich lamellar blocks having a width of about 0.5 L_(o) (e.g.,5-50 nm) within each trench. In the use of a solvent anneal, the filmcan be much thicker than L_(o), e.g., up to about +1000% of the L_(o)value. The thickness of the block copolymer material 44 can be measured,for example, by ellipsometry techniques. As shown, a thin film 44 a ofthe block copolymer material 44 can be deposited onto the spacers 36 ofthe material layer 32; this film will form a monolayer of elements withno apparent structure from a top-down perspective (e.g., lamellae in aparallel orientation).

The block copolymer material is fabricated such that each of theself-assembled polymer domains has a different solubility for a givenink chemical. The ink chemical is applied as an organic solution, eitherneat (undissolved) or combined with a solvent that will be selectivelyabsorbed into and cause one of the polymer domains to swell and becomeimpregnated with the ink chemical material. In some embodiments, the inkbut not the solvent will be selectively absorbed into one of the polymerdomains.

In some embodiments, the block copolymer can be chemically modified toinclude a functional group having chemical affinity for the inkmaterial, for example, a thiol or amine group. For example, one of theblocks can inherently contain a thiol or amine functional group, forexample, polyvinylpyridine.

The film morphology, including the domain sizes and periods (L_(o)) ofthe microphase-separated domains, can be controlled by chain length of ablock copolymer (molecular weight, MW) and volume fraction of the ABblocks of a diblock copolymer to produce lamellar, cylindrical, orspherical morphologies, among others.

For example, for volume fractions at ratios greater than about 80:20 ofthe two blocks (AB) of a diblock polymer, a block copolymer film willmicrophase separate and self-assemble into periodic spherical domainswith spheres of polymer B surrounded by a matrix of polymer A. Forratios of the two blocks generally between about 60:40 and 80:20, thediblock copolymer assembles into periodic cylindrical domains of polymerB within a matrix of polymer A. For ratios between about 50:50 and60:40, lamellar domains or alternating stripes of the blocks are formed.Domain size typically ranges from 5-50 nm.

An example of a lamellae-forming PS-b-PMMA diblock copolymer (L_(o)=32nm) to form about 16 nm wide lamellae is composed of a weight ratio ofabout 50:50 (PS:PMMA) and total molecular weight (M_(n)) of about 51kg/mol. An example of a cylinder-forming PS-b-PMMA copolymer material(L_(o)=35 nm) to form about 20 nm diameter cylindrical PMMA domains in amatrix of PS is composed of about 70% PS and 30% PMMA with a totalmolecular weight (M_(n)) of 67 kg/mol.

Although PS-b-PMMA diblock copolymers are used in the illustrativeembodiments, other types of block copolymers (i.e., triblock ormultiblock copolymers) can be used. Examples of diblock copolymersinclude poly(styrene-block-methyl methacrylate) (PS-b-PMMA),polyethyleneoxide-polyisoprene, polyethyleneoxide-polybutadiene,polyethyleleoxide-polystyrene, polyetheleneoxide-polymethylmethacrylate,polystyrene-polyvinylpyridine, polystyrene-block-polyisoprene (PS-b-PI),polystyrene-polybutadiene, polybutadiene-polyvinylpyridine,polyisoprene-polymethylmethacrylate, and polystyrene-polylactide, amongothers. Examples of triblock copolymers include poly(styrene-blockmethyl methacrylate-block-ethylene oxide).

The block copolymer material can also be formulated as a binary orternary blend comprising a SA block copolymer and one or morehomopolymers of the same type of polymers as the polymer blocks in theblock copolymer, to produce blends that swell the size of the polymerdomains and increase the L_(o) value of the polymer. The volume fractionof the homopolymers can range from 0% to about 40%. An example of aternary diblock copolymer blend is a PS-b-PMMA/PS/PMMA blend, forexample, 46K/21K PS-b-PMMA containing 40% 20K polystyrene and 20Kpoly(methylmethacrylate). The L_(o) value of the polymer can also bemodified by adjusting the molecular weight of the block copolymer.

The block copolymer film 44 is then annealed to cause the polymer blocksto phase separate and self-assemble according to the preferential andneutral wetting of the trench surfaces to form a self-assembled polymerfilm. The resulting morphology of the annealed film 46 (e.g.,perpendicular orientation of lamellae) can be examined, for example,using atomic force microscopy (AFM), transmission electron microscopy(TEM), scanning electron microscopy (SEM).

In some embodiments, the deposited block copolymer film 44 can besolvent annealed. In embodiments of a solvent anneal, the film 44 can beswollen by exposure to a vapor of a “good” solvent for both blocks, andthe vapor can then be removed. Vapors of a solvent such as benzene,chloroform or a chloroform/octane mixture, for example, can be exposedto the film 44 to slowly swell both blocks (PS, PMMA) of the film 44.The solvent and solvent vapors are then allowed to slowly evaporate todry the film 44, resulting in self-assembled polymer domains.

The block copolymer film 44 can also be thermally annealed at theannealing temperature (e.g., about 150° C.-250° C.) in an atmospherethat is saturated or nearly saturated (but not supersaturated) with asolvent in which both blocks are soluble. The solvent-saturated vapormaintains a neutral air interface in conjunction with the surfaceinterface with a neutral wetting floor 42. The existence of both neutralwetting air and surface interfaces induces the formation ofperpendicular features throughout the film 44.

Referring to FIGS. 8-8A, upon annealing a lamellar-phase block copolymerfilm 44 (e.g., PS-b-PMMA of about L₀) within a trench 34 withpreferential wetting sidewalls 38 and a neutral wetting trench floor 42(exhibits neutral or non-preferential wetting toward both blocks, e.g.,a random graft copolymer), the polymer material will self-assemble intoa film 46 composed of alternating polymer-rich blocks 48, 50 (e.g., PSand PMMA). The lamellar blocks 48, 50 are oriented perpendicular to thetrench floor 42 and parallel to the sidewalls 38, extending the lengthof the trench 34 and spanning the width (w_(t)) at an average pitchvalue at or about L_(o). The constraints provided by the width (w_(t))of the trenches 34 and the character of the copolymer compositioncombined with preferential or neutral wetting surfaces within thetrenches result, upon annealing, in a single layer of n lamellae 48, 50across the width (w_(t)) of the trench. The number “n” or pitches oflamellar blocks within a trench is according to the width (w_(t)) of thetrench and the molecular weight (MW) of the block copolymer. Forexample, depositing and annealing an about 50:50 PS:PMMA block copolymerfilm (e.g., M_(n)=51 kg/mol; L_(o)=32 nm) in an about 160 nm wide trenchwill subdivide the trench into about 5 lamellar pitches. The stampingsurface of a stamp 26 is thus defined by a lamellar array of polymerdomains that define a linear pattern of lamellar blocks, each about14-18 nm wide and several microns in length (e.g., about 10-4000 μm),and a center-to-center pitch of about 32 nm. A smaller pitch can bedialed in by using lower molecular weight diblock copolymers.

In embodiments in which a film of a cylindrical-phase block copolymer isdeposited into trenches with preferential wetting sidewalls and aneutral wetting trench floor, upon annealing, the cylinder-phasecopolymer film will self-assemble into a film composed ofperpendicular-oriented cylinders of one of the polymer blocks (e.g.,PMMA) within a polymer matrix of the other polymer block (e.g., PS)registered to the sidewalls of the trench.

FIG. 9 illustrates an embodiment of a stamp 26′ composed of an annealedcylinder-phase copolymer film 46′ in the formation of an array ofhexagonal close-packed array of perpendicular-oriented cylinders 52′within a polymer matrix 54′. The sidewalls 38′ and angled ends 40′ ofthe trenches 34′ are used as constraints to induce orientation andregistration of cylindrical copolymer domains to achieve the hexagonalcylindrical array registered to the trench sidewalls. The width (w_(t))of the trenches 34′ is at or about L_(o)*cos(π/6) or L_(o)*0.866, whichdefines the number of rows of cylinders, and the trench length (l_(t))is at or about mL_(o), which defines the number of cylinders per row.The ends 40′ of the trenches are angled to the sidewalls 38′, forexample, at an about 60° angle, and in some embodiments can be slightlyrounded. A cylindrical-phase diblock copolymer material having aninherent pitch at or about L_(o) (or blend with homopolymers) and athickness (t) of about L_(o) will self-assemble upon annealing to form ahexagonal array of cylindrical domains 52′ of the minor (preferred)polymer block (i.e., like domains such as PMMA) that are orientedperpendicular to the neutral wetting floor 42′ of the trench 34′ withina matrix 54′ of the major polymer block (e.g., PS). The minor(preferred) polymer block (e.g., PMMA) will segregate to thepreferential wetting sidewalls 38′ and ends 40′ to form a wetting layer52 a′. The hexagonal array contains n single rows of cylinders accordingto the width (w_(t)) of the trench with the cylinders 52′ in each rowbeing offset from the cylinders in the adjacent rows. Each row containsa number of cylinders, generally m cylinders, which number can varyaccording to the length (l_(t)) of the trench and the shape of thetrench end (e.g., rounded, angled, etc.) with some rows having greateror less than III cylinders. The cylinders 52′ are generally spaced apartat a pitch distance (p₁) at or about L_(o) between each cylinder in thesame row and an adjacent row (center-to-center distance), and at a pitchdistance (p₂) at or about L_(o)*cos(π/6) or 0.866 L_(o) being thedistance between two parallel lines where one line bisects the cylindersin a given row and the other line bisects the cylinders in an adjacentrow. The stamping surface 64′ of the stamp 26′ is thus defined by anarray of polymer domains that define a hexagonal or honeycomb pattern ofperpendicular-oriented cylinders 52′, each about 20-22 nm in diameterwith a center-to-center pitch of about 42 nm.

In another embodiment using a cylindrical-phase copolymer material, thetrench dimensions can be modified to use the trench sidewalls and endsas constraints to induce orientation and registration of cylindricalcopolymer domains in a single row parallel to the trench sidewalls. Thetrenches are structured to have a width (w_(t)) that is at or about1.0-1.75* the L_(o) value of the block copolymer material, a neutralwetting floor, and sidewalls and ends that are preferential wetting bythe minority (preferred) block (e.g., the PMMA block) of the diblockcopolymer (e.g., PS-b-PMMA). A cylindrical-phase diblock copolymer (orblend with homopolymers) having an inherent pitch at or about L_(o) canbe deposited into the trenches to a thickness (t₁) of about the L_(o)value of the copolymer material (as in FIGS. 7 and 7A). As illustratedin FIGS. 10 and 10A, the annealed block copolymer film self-assembles toform film 46″. The constraints provided by the width (w_(t)) of trench34″ and the character of the block copolymer composition combined with aneutral wetting trench floor 42″ and preferential wetting sidewalls 38″results in a one-dimensional (1D) array or single row ofperpendicular-oriented cylindrical domains 52″ of the minority(preferred) polymer block (e.g., PMMA) within a matrix 54″ of the majorpolymer block (e.g., PS), with the preferred block segregating to thesidewalls 38″ of the trench 34″ to form a wetting layer 52 a″. In someembodiments, the cylinders have a diameter at or about 0.5 L_(o) (e.g.,about 20 nm), the number n of cylinders in the row is according to thelength of the trench, and the center-to-center distance (pitch distance)(p) between each like domain (cylinder) is at or about L_(o) (e.g.,about 40 nm). The resulting stamping surface 64″ of the stamp 26″ isdefined by an array of polymer domains that define a single row ofperpendicular-oriented cylinders 52″, each about 20-22 nm in diameterwith a center-to-center pitch of about 42 nm.

Referring now to FIGS. 11 and 11A, in yet another embodiment using acylindrical-phase copolymer material, the trenches 34′″ can bestructured with preferential wetting surfaces 38, 40, 42 to induceformation of half-cylinder copolymer domains 56′″ in a polymer matrix54′″ that are in a parallel orientation to the trench floors 42′″ andregistered to the sidewalls 38′″. A preferentially wetting floor 42′″can be provided, for example, by a layer 58′″ of oxide, silicon nitride,silicon oxycarbide, among others. The stamping surface 64′″ of the stamp26″″ is defined by an array of polymer domains that define lines ofhalf-cylinders, each about 20-22 nm wide and several microns in length(e.g., about 10-4000 μm), and a center-to-center pitch of about 42 nm.

In another embodiment of the invention, graphoepitaxy (topographicfeatures, e.g., sidewalls, ends, etc.) is used to influence theformation of arrays in one dimension, and the trench floors provide awetting pattern that can be used to chemically control formation of thearrays in a second dimension. For example, as illustrated in FIGS. 12and 12A, a neutral wetting material 30″″ (e.g., random copolymer) can beformed on the base substrate 28″″ and crosslinked in select regions60″″, such as by photo-exposure through a reticle or a patterned mask(e.g., photoresist). As shown, the non-crosslinked regions of theneutral wetting material 30″″ have been removed (e.g., by wet processingusing a solvent) to expose the sections 62″″ of the underlying basesubstrate 28″″, resulting in a pattern of discrete regions 60″″ of thecrosslinked neutral-wetting material 30″″ (random copolymer) andsections 62″ of the exposed preferential-wetting base substrate 28″.

As depicted in FIGS. 13-13B, the material layer 32″″ can then be formedand trenches 34″″ etched to expose the sections 60″″ of the neutralwetting material 30″″ and sections 62″″ of the exposed base substrate10″″ on the trench floors 18″″ as a series of stripes orientedperpendicular to the trench sidewalls 38″″. The trench floors 42″″ arethus defined by alternating preferential wetting sections 62″″ (basesubstrate 28″″) and neutral wetting sections 60″″ (a mat of thecrosslinked random copolymer 30″″). In some embodiments, each of thesections can have a width (w_(r1)) at or about L_(o), and in otherembodiments, the neutral wetting sections 60″″ can have a width (w_(r2))at or about nL_(o) and the preferential wetting sections 62″ have awidth at or about L_(o). The trench sidewalls 38″″ and ends 40″″ (e.g.,of oxide) are preferential wetting to the minority (preferred) block ofthe block copolymer.

A cylindrical-phase block copolymer film (e.g., pitch L_(o)) can then becast or spin-coated into the trenches 34″″ to a film thickness (t) ofabout L_(o) and annealed. As illustrated in FIGS. 14-14B, the differingwetting patterns on the trench floor 42″″ imposes ordering on thecylindrical-phase block copolymer film as it is annealed, resulting in a1D array of alternating perpendicular-oriented cylinders 52″″ andparallel-oriented half-cylinders 56″″ for the length (nL_(o)) of eachtrench.

After the copolymer film is annealed and ordered, the film can then betreated to crosslink the polymer segments (e.g., the PS segments) to fixand enhance the strength of the self-assembled polymer blocks. Thepolymers can be structured to inherently crosslink (e.g., upon exposureto ultraviolet (UV) radiation, including deep ultraviolet (DUV)radiation), or one or both of the polymer blocks of the copolymermaterial can be formulated to contain a crosslinking agent.

Optionally, the unstructured thin film 44 a of the block copolymermaterial outside the trenches (e.g., lamellae in a parallel orientationon spacer 36 in FIG. 7A) can then be removed, as illustrated in FIGS. 8and 8A. In embodiments in which the ink chemical would be absorbed bythe film 44 a, the film would be removed.

For example, the trench regions can be selectively exposed through areticle (not shown) to crosslink only the annealed and self-assembledfilm 46 within the trenches 34, and a wash can then be applied with anappropriate solvent (e.g., toluene) to remove the non-crosslinkedportions of the block copolymer material 44 a on the spacers 36, leavingthe registered self-assembled film within the trench and exposing thesurface of material layer 32 on the spacers 36 above/outside thetrenches. In another embodiment, the annealed film 46 can be crosslinkedglobally, a photoresist material can be applied to pattern and exposethe areas of the film 44 a over the spacers 36 outside the trenchregions, and the exposed portions of the copolymer film can be removed,for example, by an oxygen (O₂) plasma treatment.

The resulting stamp is structured with a stamping surface 64 composed ofan ordered array of polymer domains (e.g., 48, 50) in the desiredpattern for stamping onto a receptor substrate. The stamp can then beinked and brought into contact with the receptor substrate to producethe pattern on the substrate.

The ink chemical material is selected such that it will be absorbedselectively into a polymer domain of the self-assembled polymer film byVan der Waals forces or other non-covalent force or bond (e.g., hydrogenbond, etc.) and will form a self-assembled monolayer (SAM) on thereceptor substrate. The ink chemical can include one or more functionalgroups that chemically react with the receptor substrate. The chemicalaffinity between the ink material and the receptor substrate is greaterthan the chemical affinity between the ink material and the polymerdomain in which it is absorbed.

In embodiments of the invention, the ink chemical can have amino, thiol,alcohol or alkyne functional groups. Examples of ink chemicals includethiols such as 2-aminoethanethiol, aminothiophenol, cysteine,homocysteine, leucinethiol, 2-butylaminoethanethiol,2-cylcohexylaminoethanethiol, etc.; mercaptoalcohols such asmercaptoethanols (e.g., 2-mercaptoethanol (HS—CH₂CH₂OH)),mercaptopropanols (e.g., 2-mercaptopropanol) and mercaptobutanols (e.g.,4-mercapto-1-butanol, 2-mercaptobutanol); and acetylenics withhydrocarbon tails or other functional groups such as alcohols, thiols,amines, halides, etc., (e.g., carboxylates such as propiolic acid,4-butynoic acid, 5-pentynoic acid), and the like.

The ink chemical material is in the form of an organic solution suchthat it will diffuse into and be selectively absorbed by one of thepolymer domains causing the polymer domain to swell. The ink chemicalmaterial can be in the form of a neat (undiluted) solution or combinedwith an organic solvent that will promote diffusion of the materialselectively into the selected polymer domain. Examples of solvents thatcan be utilized include methanol, ethanol, isopropanol, ethylene glycol,propylene glycol and acetic acid. Typically, the concentration of theink chemical material in solution is about 1-10 k mM.

In another embodiment, the ink chemical material can be provided in avaporous form, which can provide a higher level of control with respectto the amount of ink material that is absorbed into the stamp. The stampwould be exposed to a vapor of the ink chemical for a sufficient timeperiod for absorption of an adequate quantity of the ink chemical by thepolymer domain.

FIGS. 15-18 illustrate an embodiment of a stamping process utilizing astamp 26 according to the invention, as depicted in FIGS. 8 and 8A.

Referring to FIG. 15, a stamping process can be conducted by applying(arrows ↓) a solution of the ink chemical material (either neat or in asolvent) 66 onto the stamping surface 64 or, in other embodiments, byexposing the stamping surface 64 to a vapor of the ink chemical. Thecontact of the ink chemical solution with the stamping surface 64 of thestamp is for a time effective to enable the ink material to diffuse intoand be selectively absorbed by the targeted polymer domain.

Upon contact of the stamp with the ink chemical, the polymer domain 50with affinity for the ink chemical solution (e.g., PS domain) is swelledby absorption of the ink chemical solution, as illustrated in FIG. 16.The other polymer domain 48 with substantially no affinity for the inkchemical (e.g., PMMA domain) remains unchanged. This results in thestamping surface 64 of the stamp 26 having a relatively corrugatedsurface that defines the lines of the swollen polymer domains 50.

As illustrated in FIG. 17, a receptor substrate 68 is then brought intocontact (arrows ↓) with the swollen and ink-containing polymer domains50 situated on the stamping surface 64 of the stamp 26 to effecttransfer of the ink material 66 onto the receptor substrate 68,resulting in a pattern 70 on the receptor substrate, as shown in FIGS.18 and 18A. The ink chemical material 66 is transferred from the stamp26 by chemical bonding of one or more functional groups of the inkmaterial with a functional group(s) on the surface of the receptorsubstrate 68.

Examples of the receptor substrate 68 include silicon oxide, siliconwafers, silicon-on-insulator (“SOI”) substrates, silicon-on-sapphire(“SOS”) substrates, and other semiconductor substrates such assilicon-germanium, germanium, gallium arsenide and indium phosphide,chalcogenide-class of materials, magnetic materials (e.g., Ni, Fe, Co,Cu, Ir, Mn, Pt, Tu, etc.), and other substrates used in disk drives oroptical storage devices. Optionally, the receptor substrate 68 can bemodified to incorporate functional groups that enhance chemical bondingand transfer of the ink material from the stamp/template (e.g., stamp26), as indicated in Table 1 (below). Substrates modified with aglycidoxy functionality will be reactive to inks having amine or thiolfunctional groups. Substrates modified with an isocyanate functionalitywill be reactive to inks having alcohol or amino functional groups.Substrates modified with chlorosilyl groups will be reactive to inkswith amino, alcohol or thiol functional groups. Alkylazido-modifiedsubstrates will be reactive to inks with alkyne functional groups. Forexample, a silicon oxide substrate can be modified with azide groups tofacilitate binding of an acetylenic carboxylate ink.

Table 1 (below) provides examples of ink chemical materials that can beused for selective absorption by one of the polymer block domains (i.e.,PMMA) of a stamp according to the invention, and embodiments of receptorsubstrate modifications that can be used in combination with the inkchemical material to effect transfer of the ink onto the receptorsubstrate to form SAMs in a stamped pattern.

Ink Material Receptor Substrate modification Thiols, such as:Glycidoxy-modified substrates such as SiO₂ 2-aminoethanethiol graftedwith a glycidoxypropyl(trialkoxy) aminothiophenol silane (e.g.,glycidoxypropyl cysteine trimethoxysilane) homocysteineIsocyanato-modified substrates such as SiO₂ leucinethiol grafted with aisocyanatopropyl(trialkoxy) 2-butylaminoethanethiol silane (e.g.,isocyanatopropyl triethoxysilane, 2-cylcohexylamino- isocyanatopropyltrimethoxysilane, etc.) ethanethiol Chlorosilyl-modified substrates suchas chlorine-terminated silicon (Si—Cl) (e.g., from H-terminated siliconexposed to Cl₂ gas) Mercaptoalcohols, Isocyanato-modified substratessuch as SiO₂ such as: grafted with a isocyanatopropyl(trialkoxy)mercaptoethanols silane (e.g., isocyanatopropyl triethoxysilane,mercaptopropanols isocyanatopropyl trimethoxysilane, etc.)mercaptobutanols Chlorosilyl-modified substrates such aschlorine-terminated silicon (Si—Cl) Acetylenics with Alkylazido-modified substrates such as hydrocarbontails or other SiO₂ grafted with6-azidosulfonylhexyl functional groups such as (triethoxy) silane, orwith an alcohols, thiols, amines, 11-azidoundecyl group halides, etc.,such as: (e.g., formed from 11-bromoundecyl propiolic acid (triethyoxy)silane reacted with sodium (or acetylene azide). monocarboxylic acid)butynoic acid pentynoic acid

An alkylazido-modified receptor substrate 68 can be prepared, forexample, as a silicon dioxide (SiO₂) substrate grafted with6-azidosulfonylhexyl (triethoxy)silane or with an 11-azidoundecyl groupmonolayers that can be formed by grafting 11-bromoundecyl(triethyoxy)silane to a SiO₂ substrate then derivatizing with sodiumazide, as described, for example, by Rozkiewicz et al., Angew. Chem.Int. Ed. Eng., 2006, 45, 5292-5296. A chlorosilyl-modified receptorsubstrate 68 can be prepared, for example, as chlorine-terminatedsilicon (Si—Cl) by chlorination of hydrogen-terminated silicon surfacesby exposure to chlorine gas (Cl₂) (e.g., at 80° C. or exposure to atungsten lamp), as described, for example, by Zhu et al., Langmuir,2006, 16, 6766-6772.

The temperature during the stamping process generally ranges from aboutroom temperature (20° C.) to near the boiling point of the ink chemicalsolution. Contact of the stamp 26 with the receptor substrate 68 is fora time effective to enable chemical bonds to form between functionalgroups on the receptor substrate and the ink chemical material 66,generally about 1 minute to about 4 hours, and typically about 1-15minutes.

The receptor substrate and the ink material may react to form a urea orurethane linkage through a mercapto alcohol, a disulfide linkage througha thiol (R—SH) functional group, a bond involving acid/base groups, oran amine linkage through an amine/epoxide reaction of a triazole imagethrough reaction between an azide and alkyne. Diffusion (or othertransfer mechanism) of the ink material from the polymer domains of thestamp onto the receptor substrate (where the ink reacts) can create aconcentration gradient, which then draws additional ink onto the surfaceof the receptor substrate from the inked polymer domains.

Upon completion of the ink transfer to the receptor substrate, the stampis then removed leaving the ink chemical material 66 as a pattern 70 onportions of the receptor substrate 68 corresponding to the inked polymerdomains 50 on the stamping surface 64 of the stamp 26 and exposedportions 72 of the substrate, as shown in FIGS. 18 and 18A. In someembodiments, the ink chemical material is processed to form aself-assembled monolayer (SAM) on the surface of the receptor substrate68. The stamp 26 may then be re-inked, if needed, for further stampingof the same or another receptor substrate.

The ink pattern 70 on the receptor substrate 68 has identical orsubstantially identical resolution to the pattern of the inked polymerdomains on the stamping surface 64 of the stamp 26. The patterned stamp26 can be used to produce features (pattern 70) on the receptorsubstrate that are sub-lithographic, for example, a thickness of about1-10 angstroms, and lateral width (w_(p)) that corresponds to thedimension (width (w_(pd))) of the pattern of the “inked” polymer domainson the stamping surface 64 of the stamp 26 (FIG. 17).

In the embodiment illustrated in FIGS. 18 and 18A, the ink (e.g., SAM)pattern 70 formed using the stamp 26 having a stamping surface 64composed of a lamellar array of polymer domains defines a linear patternof fine, parallel lines of nanometer-scale to sublithographic dimensionsabout 5-50 nm wide and several microns in length (e.g., about 10-4000μm), and a center-to-center pitch of about 10-100 nm. Stamp 26′″ (FIGS.11 and 11A), for example, also provides a stamping surface havingparallel lines of polymer domains. In other embodiments, the stamp canhave a stamping surface composed of a cylindrical array of polymerdomains as described, for example, with respect to stamps 26′ and 26″(FIGS. 9-10A).

After applying the ink pattern on the receptor substrate, furtherprocessing may be conducted as desired.

For example, the inked pattern 70 of the stamped regions or elements 66shown in FIG. 18A, can be used to guide the formation of etch masks topattern portions of the underlying receptor substrate 68.

In one embodiment, the inked pattern 70 of elements 66 can be formed asa chemically differentiated surface in a pattern of hydrophobic andhydrophilic materials (or neutral and preferential-wetting materials),which can be used as a template to guide and chemically control theself-assembly of a block copolymer to match the template pattern ofelements on the receptor substrate. For example, as depicted in FIGS. 18and 18A, using a template such as stamp 26 (FIG. 16), an ink materialthat will form a SAM composed of a hydrophobic material such asoctadecylthiol (ODT) can be transferred as a pattern 70 of elements 66(e.g., parallel lines) onto a receptor substrate 68 that has an epoxidesurface. Unstamped regions 72 of the substrate adjacent to the lineelements 66 can be made hydrophilic by reacting the exposed substratewith a material such as 11-hydroxyundecylthiol. The pattern ofhydrophobic material line elements 66 and the hydrophilic substrateregions 72 on the substrate can then be used as a template for guidedself-assembly of a block copolymer material.

Referring to FIG. 19, a block copolymer material having domains that areselectively wetting to the template (seed layer) formed by thehydrophobic line elements 66 and the hydrophilic substrate regions 72,can be deposited as a film 74 onto the substrate. The copolymer film 74can then be annealed to form a self-assembled polymer film 76 withlamellae 78, 80 registered to the hydrophobic and hydrophilic regions66, 72 of the template below, as illustrated in FIG. 20. Then, as shownin FIG. 21, one of the polymer domains (e.g., lamellae 80) of theself-assembled film 76 can be selectively removed and the resulting film82 can be used as a mask to etch (arrows ↓↓) the underlying substrate68, for example, by a non-selective RIE etching process, to delineate aseries of openings 84 (shown in phantom). Further processing can then beperformed as desired, such as filling the openings 84 with a material 86as shown in FIG. 22, for example, with a dielectric material to separateactive areas, or with a conductive material such as a metal or otherconductive material to form nanowire channel arrays for transistorchannels, semiconductor capacitors, and other structures that can extendto an active area or element in the substrate or an underlayer. Furtherprocessing can then be performed as desired. The self-assembly of blockcopolymers to an underlying chemical pattern is rapid relative to othermethods of “top-down” or graphoepitaxy ordering and registration.

In other embodiments, the inked pattern of elements 66 can be used as atemplate for selective deposition of a hydrophobic or hydrophilicmaterial onto either the inked elements 66 or the unstamped areas 72 ofthe substrate.

For example, referring to FIG. 23, the inked pattern of elements 66′ canbe used as an “anti-seed” guide or template for the global applicationand selective deposition of a material 74′ that is chemically differentfrom the stamped regions (elements) 66′ onto adjacent exposed regions72′ of the substrate 68′. For example, elements 66′ composed of ahydrophobic ink material (e.g., octadecyl thiol) can be stamped onto thesubstrate 68′, and a hydrophilic material 74′ (e.g., an oxide) can beselectively applied to the non-stamped substrate areas 72′, for example,by a vapor deposition, resulting in the structure shown in FIG. 23. Theresulting film 82′ can be used as a mask to etch (arrows ↓↓) theunderlying substrate 68′ to form openings 84′, as depicted in FIG. 24.

In another embodiment, as shown in FIG. 25, elements 66″ can be used asa seed material for the selective deposition of additional material 74″to increase the thickness and/or hardness of the elements 66″ andproduce a hard mask for etching the substrate 68″. For example, elements66″ can be formed from acetylenic hydrocarbons or esters of acetyleniccarboxylates with hydrocarbon conjugates (e.g., hexylpropynoate ester),with subsequent selective deposition of an inorganic material 74″ suchas silicon oxide to increase the thickness and/or hardness of theelements 66″. In another example, a material 74″ such as silicon nitridecan be selectively deposited onto the elements 66″ by ALD methods toform a hardmask 82″ composed, for example, of a series of linesaccording to the pattern of the elements 66″. In other embodiments,elements 66″ can be formed as a seed layer from an ink material having afunctional group on its tail end (e.g., ink chemical with a brominefunctional group) that will selectively initiate polymer growth, and anatom transfer radical polymerization (ATRP) can then be conducted to addadditional polymer material 74″ to increase the thickness and/orhardness of the elements 66″ and produce a hard mask for etchingopenings 84″. The hardmask 82″ can be then used, for example, to maskthe etch of the underlying substrate 68″ (e.g., film stack, etc.) toform openings 84″, as shown in FIG. 26.

Another embodiment of the invention illustrated in FIGS. 27-32, utilizeschemical patterning of a substrate to direct self-assembly of a blockcopolymer. In some embodiments, the process utilizes a stamp/template 88that is formed with transparent sections 90, non-transparent sections92, and a stamping surface 94. The transparent sections 90 are composedof a material that is substantially transparent to UV or DUV radiationin order to allow light to pass therethrough, for example, glass (e.g.,quartz (SiO₂)), calcium fluoride (CaF₂), diamond, or a transparentplastic or polymeric material, and the non-transparent (opaque) sections92 can be composed, for example, of a elastomeric polymer material suchas poly(dimethylsiloxane) (PDMS).

As shown in FIG. 27, the stamping surface 94 can be coated with a thinfilm 96 of a polymerizable neutral wetting material that exhibitsnon-preferential or neutral wetting toward the blocks of a blockcopolymer, such as a random block copolymer (e.g., PS-r-PMMA). Thetemplate 88 can then be pressed (arrow ↓) onto a receptor substrate 68(e.g., a preferential wetting material such as silicon (with nativeoxide), oxide, etc.) as shown in FIG. 28 to transfer the polymermaterial 96 onto the substrate 68. Then, as illustrated in FIG. 29, aradiation source (e.g., UV or DUV radiation) can then be transmitted(arrows ↓↓) through the transparent sections 90 of the stamp/template 88to photolytically crosslink discrete sections 98 of the polymer material96 on the substrate 68. The template 88 can then be removed from contactwith the receptor substrate 68, leaving the crosslinked polymer sections98 and non-crosslinked polymer material 100, as depicted in FIG. 30.

Further processing can then be conducted as desired. For example, asshown in FIG. 31, the non-crosslinked polymer material 100 can beremoved, for example, by wet processing by a chemical dissolutionprocess using a solvent to expose sections 102 of the receptor substrate68, resulting in discrete neutral wetting sections 98 composed of thecrosslinked polymer material (e.g., crosslinked random copolymer) andpreferential wetting sections 102 composed of the exposed receptorsubstrate (e.g., oxide). A block copolymer material can then be cast orspin-coated onto the chemically differentiated surface and annealed toform a self-assembled block copolymer layer 104. As illustrated in FIG.32, the annealed block copolymer film 104 will register to the differingwetting patterns (98, 102) on the receptor substrate 68, for example, toform lamellae 106, 108 as shown. The resulting film 104 can be furtherprocessed, for example, to selectively remove one of the polymer blocksto produce a hard mask for use in a dry etch to transfer the patterninto the underlying substrate material.

Patterning a substrate using conventional lithographic techniques hasbeen hampered by difficulties such as high costs and/or incompatibilitywith high throughput production methods. With embodiments of the presentinvention, a stamp can be prepared using conventional lithography (toform the trenches) but, because the stamp can be used repeatedly topattern multiple substrates, the production cost per stamped substrateis reduced. In addition, the use of the stamped pattern (e.g., SAM inkpattern 70) for chemically controlling the formation of a self-assembledblock copolymer film, can subsequently provide an etch mask on ananoscale level that can be prepared more inexpensively than by electronbeam lithography or EUV photolithography. The feature sizes produced andaccessible by this invention cannot be prepared by conventionalphotolithography.

In another embodiment of the invention illustrated in FIGS. 33-60A, theordering of a self-assembling block copolymer material (e.g., film) isinduced and directed by overlaying a topographically flat stamp that ischemically patterned on its surface. The chemically patterned stampoverlaid on a BCP film cast onto a substrate that has been globallymodified to be equally wetting to both blocks of the BCP will directself-assembly of the BCP film to match the pattern on the stamp. Thepresent embodiment of the invention achieves a pattern transfer to ablock copolymer (BCP) without leaving a physically formed impression inthe substrate and without a transfer of material to the substrate or theBCP material.

FIG. 33 illustrates a substrate (generally 110) to be patterned. Thesubstrate 110 can be composed of a base material 112, which can be, forexample, silicon, silicon oxide, silicon nitride, silicon oxynitride,silicon oxycarbide, among other material. As shown, a non-preferentialor neutral wetting material 114 (equal affinity for blocks of thecopolymer) is formed over the base material.

The neutral wetting material 114 can be formed, for example, by blanketcoating a random copolymer material onto the base material 112 bycasting or spin-coating, and fixing the polymer material in place bygrafting (on an oxide substrate) or by thermally or photolyticallycrosslinking (any surface). For example, a material that is neutralwetting to a PS-b-PMMA block copolymer can be formed from a thin film ofa photo-crosslinkable random PS:PMMA copolymer, for example, PS-r-PMMA(60% PS) grafted to an oxide substrate.

As previously described, a neutral wetting layer can also be formed on abase material 112 such as an oxide by grafting and heating a randomcopolymer of polystyrene (PS) and polymethacrylate (PMMA) with a few %(e.g., less than or equal to about 5%) hydroxyl group(s) (e.g.,2-hydroxyethyl methacrylate (P(S-r-MMA-r-HEMA)) on the base material. Inanother embodiment, a surface that is neutral wetting to PS-b-PMMA canalso be prepared by spin coating and crosslinking a benzocyclobutene- orazidomethylstyrene-functionalized random copolymer of styrene and methylmethacrylate (e.g., poly(styrene-r-benzocyclobutene-r-methylmethacrylate (PS-r-PMMA-r-BCB)) on the base material.

In yet another embodiment, a base material 112 of silicon (with nativeoxide) can be treated by a fluoride ion etch (e.g., with aqueous HF,buffered HF or NH₄F, HF vapor treatment, etc.) or a hydrogen plasma etchas previously described, to form hydrogen-terminated silicon, which isneutral wetting to a block copolymer material such as PS-b-PMMA. AnH-terminated silicon material 114 can be further processed by graftingof a random copolymer such as PS-r-PMMA onto the material 114 (e.g., insitu free radical polymerization of styrene and methyl methacrylate witha di-olefinic linker).

Referring now to FIG. 34, a lamellar- or cylindrical-phase blockcopolymer material 116 is then cast as a film onto the neutral wettingmaterial 114 on the substrate 110. The block copolymer material 116 hasan inherent pitch at or about L_(o) (or a ternary blend of blockcopolymer and homopolymers blended to have a pitch at or about L_(o)).The block copolymer material 116 can be deposited by spin casting orspin-coating from a dilute solution (e.g., about 0.25-2 wt % solution)of the copolymer in an organic solvent such as dichloroethane (CH₂Cl₂)or toluene, for example. The thickness (t) of the block copolymermaterial 116 is at or about L_(o).

The block copolymer material 116 is then induced to self-assemble bycontact with a stamp, which, according to the invention, istopographically flat and chemically patterned on its surface.

FIGS. 35-39B illustrate an embodiment of a process for forming a mastertemplate for forming a stamp for use in inducing self-assembly of ablock copolymer material on a substrate. The master template (generally118), which is topographically flat, is prepared by forming a pattern ofchemically differentiated areas on the surface of a base substrate 120.The base substrate 120 can be composed, for example, of silicon dioxideor gold.

Referring to FIG. 35, in one embodiment, a hydrophilic material 122 onthe base substrate 120 can be micropatterned to form the chemical mastertemplate 118. The hydrophilic material 122 can be, for example, silicon(with native oxide), oxide (e.g., silicon oxide, SiO_(x)), indium tinoxide (ITO), silicon nitride, silicon oxycarbide, silicon oxynitride. Inanother embodiment, the hydrophilic material 122 can be composed of ametal, for example, gold, silver, copper, palladium or platinum, on thebase substrate 122 and an overlying SAM of an alkane thiol such ashydroxyundecylthiol (HUT), or other hydrophilic alkane thiol. Thehydrophilic material 122 can be formed on the base substrate 120 as amonolayer (SAM) of about 0.5-5 nm thick.

As shown in FIG. 36, a layer of resist material 124 can be formed on thehydrophilic material 122, and then developed in a desired pattern andremoved (FIGS. 37-37B) to expose portions of the hydrophilic material122. The resist material 124 can be patterned using a lithographic toolhaving an exposure system capable of patterning at the scale of at orabout L_(o) (10-100 nm). The material for the resist 124 is selectedbased on the required sensitivity and compatibility with the exposuresystem that is used. Such exposure systems include, for example, extremeultraviolet (EUV) lithography, electron beam (e-beam) lithography,immersion lithography, and proximity X-rays as known and used in theart. The pattern formed in the resist material 124 can be composed, forexample, of a series of linear openings (stripes) 126, as shown in FIGS.37-37B.

Referring now to FIGS. 38-38B, a hydrophobic material 128 can then bedeposited onto the exposed sections of the hydrophilic material 122using the resist 124 as a mask. The hydrophobic material 128 can be, forexample, an alkyl trialkoxysilane such as methyltrimethoxysilane,methyltriethoxysilane, methyltriisopropoxysilane, ethyltrimethoxysilane,ethyltriethoxysilane, n-propyltrimethoxysilane andn-propyltriethoxysilane; an alkylthiolate such as dodecanethiol oroctadecanethiol (ODT); among others. The hydrophobic material 128 can bedeposited as a monolayer (e.g., self-assembled monolayer (SAM)) of about0.5-5 nm thick.

As illustrated in FIGS. 39-39B, the resist 124 can then be stripped toexpose the previously masked portions of the hydrophilic material 122.The resulting master template 118 now bears a chemically patternedsurface 130 composed of lines of the hydrophobic material 128 (e.g.,alkyl trialkoxysilane) adjacent to lines of the hydrophilic material 122(e.g., oxide). For example, a master template 118 can be prepared with asurface patterned with hydrophobic SAM 128 of octadecanethiol (ODT)adjacent to a hydrophilic SAM 122 of 11-hydroxyundecane-1-thiol (HUT),as described by van Poll et al., Angew. Chem. Int. Ed.: 46, 6634-6637(2007).

The hydrophilic 122 and hydrophobic 128 material elements on the surfaceof the master template 118 are dimensioned with a width (w₁) thatmatches or substantially matches the inherent self-assembled structure(e.g., L_(o) value) of the block copolymer material (BCP) 116 that isdeposited on the substrate 110 (FIG. 34) in those sections of thepolymer material 116 where self-assembly into perpendicular-orientedstructures (e.g., lamellae, cylinders) is desired. In areas of thepolymer material 116 where a lack of formation of perpendicular-orientedelements is desired, a hydrophobic region 128 a (FIG. 39) (orhydrophilic region) can be formed with dimensions (i.e., width (w₂))that are greater than the L_(o) value of the BCP material 116.

Referring to FIG. 40, in another embodiment of forming a chemical mastertemplate 118′, a hydrophobic material 128′ (e.g., an alkyltrialkoxysilane) can be blanket deposited onto a base substrate 120′such as silicon or silicon oxide, for example. The hydrophobic material128′ can then be patterned and removed using a resist 124′ as a mask asshown in FIGS. 41-41B, to expose portions of the base substrate 120′.Then, as depicted in FIGS. 42-42B, the exposed base substrate 120′ canthen be selectively oxidized to form a hydrophilic monolayer (SAM) 122′,or in other embodiments, a hydrophilic material (e.g., oxide, SiN,alkane thiol, etc.) can be deposited onto the exposed base substrate120′. Then, as illustrated in FIGS. 43-43B, the resist 124′ can bestripped, with the surface 130′ of the master template 118′ now bearinga pattern of lines of the hydrophobic material 128 a′ adjacent to linesof the hydrophilic material 122′.

Using the master template 118 (e.g., FIG. 39) as a guide, a stamp(generally 132) is then formed with hydrophilic and hydrophobic elementsin a mirror image of the pattern of elements on the master templatesurface. The chemically differentiated surface of the stamp 132 can thenbe used to direct self-assembly of the block copolymer material 116 onthe substrate 110 (FIG. 33).

Referring to FIGS. 44-44B, in some embodiments, a soft, flexible orrubbery material 134 such as a polydimethylsiloxane (PDMS) elastomer orother elastomeric, crosslinkable polymer material (e.g., silicones,polyurethanes, etc.) is deposited onto the chemically patterned surface130 of the master template 118 to form a stamp 132. The unmodifiedsurface of a PDMS material is hydrophobic. To modify the surface of thestamp, the polymer material can be prepared as a mixture of theelastomeric polymer with different functional small molecules, e.g., ahydrophilic molecule 136 a and a hydrophobic molecule 136 b. Asillustrated in FIGS. 45-45B, preferential wetting by molecules 136 a,136 b over the polymer material 133 against the master template 117(arrow ↓) directs the migration and preferential accumulation(self-assembly) of the small molecules 136 a, 136 b at the surface 138of the polymer stamp 132 in response to the hydrophilic 122 andhydrophobic 128 regions or elements on the functionalized surface 130 ofthe master template 118. During curing, a crosslinking agent of thepolymer material 134 reacts with the small molecules 136 a, 136 b andwith functional groups of the polymer to “freeze” the pattern of smallhydrophilic and hydrophobic molecules 136 a, 136 b into the polymer(e.g., PDMS elastomer) stamp 132 against the hydrophilic 122 andhydrophobic 128 surfaces, respectfully, of the master template 118. Theresulting stamp 132 has a flat surface 138 that bears a pattern ofsub-micrometer features of different chemical functionalities(hydrophilic 136 a and hydrophobic 136 b) that replicates the pattern ofhydrophilic (122) and hydrophobic (128) elements on the master template118.

For example, a PDMS elastomer material, such as SYLGARD® 184 (DowCorning), can prepared as a mixture of PDMS and small functionalhydrophobic and hydrophilic molecules (e.g., vinyl-terminated moleculeswith different head groups), as described by van Poll et al., Angew.Chem. Int. Ed.: 46, 6634-6637 (2007). Examples of small hydrophobicmolecules include perfluorinated alkenes (e.g., 1H, 1H,2H-perfluorodecene), vinyl esters (e.g., alky 2-bromo-2-methyl propionicacid ester), and hydrocarbon alkenes (e.g., 11-undecene), among others.Examples of small hydrophilic molecules include oligo(ethylene glycol)methacrylate (OEGMA), undec-11-enyl hexaethylene glycol monomethyl ether(PEG₆ derivative), and vinylic (mono- or divinyl) poly(ethylene glycol),among others. The PDMS can be mixed, for example, with equimolar amountsof a small amount of the small molecules, generally less than about 5 wt% (e.g., about 2-3 wt %). During curing, the molecules willself-assemble according to the functionalized monolayer on the templatesurface and react with the PDMS backbone by a hydrosilylation reactionduring curing.

Referring now to FIGS. 46 and 47 and 47A, the now chemicallyfunctionalized polymer stamp 132 can then be removed (arrows ↑↑) fromthe surface 130 of the master template 118. For example, a solvent suchas water (arrows ↓↓) can be applied or the stamp/template complex soakedin the solvent, which will permeate and swell the stamp body 132 andweaken the interfacial bonds on the hydrophilic areas, and the stamp canthen be peeled from the surface of the master template, as shown in FIG.46.

As illustrated, the surface 138 of the stamp 132 is chemicallydifferentiated according to the pattern of hydrophilic and hydrophobicelements on the master template 118. The surface of the stamp 132 iscomposed of hydrophilic lines 136 a that are preferential wetting to onedomain of the block copolymer (e.g., PMMA) and hydrophobic lines 136 bthat are preferential wetting to the other block of the block copolymer(e.g., PS). As on the master template, the dimensions (i.e., width (w₁))of the lines 136 a, 136 b match or substantially match the dimensions(i.e., w₁) of the hydrophilic lines 122 and hydrophobic lines 128,respectively, on the surface 130 of the master template 118, as well asthe L_(o) value of the block copolymer material (BCP) 116 on thesubstrate 110 (FIG. 34). The stamp 132 includes a hydrophobic section136 b ₁ that has a width (w₂) that corresponds to the dimensions (w₂) ofthe hydrophobic section 128 a on the chemical master 118, which isgreater than the BCP L_(o) value.

Referring now to FIG. 48, the chemically patterned surface 138 of thestamp 118 is now brought into contact with a surface 140 of the blockcopolymer material 116 situated on the neutral wetting material 114 onthe substrate 110, for example, by pressing the stamp surface 138 ontothe block copolymer material (FIG. 49). The rubbery or flexible body ofthe stamp 132 allows the stamp to conform to the topography of the blockcopolymer material 116. As depicted in FIG. 50, the block copolymermaterial 116 is then annealed (arrows ↓↓) while in contact with thechemically patterned stamp surface to form a self-assembled polymermaterial 142.

The chemical pattern of hydrophilic and hydrophobic lines 136 a, 136 bon the surface of the stamp 132 will direct the self-assembly andperpendicular ordering of the polymer domains of the block copolymermaterial 116 in regions in which the pitch (w₁) of the elements 136 a,136 b on the stamp surface is at or about the inherent pitch or L_(o)value of the block copolymer material 116.

For example, as depicted in FIGS. 50 and 50A, in the use of alamellar-phase block copolymer (e.g., PS-b-PMMA), during the anneal, thePMMA block will align with and preferentially wet the hydrophilicmaterial (lines) 136 a on the surface of the stamp 132 and the PS blockwill align with and preferentially wet the hydrophobic material (lines)136 b to form lines of PMMA lamella 144 a and PS lamella 144 b. Theneutral wetting material 114 on the substrate 110 ensures that theperpendicular-oriented lamellae extend completely through theself-assembled polymer material 142 from the interface with the neutralwetting material 114 to the surface 138 of the stamp 132 on those lines136 a, 136 b that have a pitch (w₁) that is at or about the L_(o) valueof the block copolymer material.

In regions of the substrate 110 where subsequent patterning (using theself-assembled BCP layer as a mask) is not desired, the contact of theblock copolymer material with a stamp region (e.g., 136 b ₁) which has awidth (w₂) that is greater than the L_(o) value of the block copolymerand is preferential wetting to only one domain of the block copolymer,will result in the formation of parallel-oriented lamellae 144 a ₁, 144b ₁ for a corresponding width (w₂) within the self-assembly polymermaterial 142.

Referring now to FIGS. 51 and 52, the stamp 132 is then removed fromcontact (↑↑) with the surface of the self-assembled polymer layer 142.To break the adhesive forces (e.g., Van der Waals forces) and lift thestamp from the polymer surface, in some embodiments, the stamp/solventcomplex can be soaked in a solvent (e.g., water, isopropyl alcohol,acetic acid, etc.) that will permeate and swell the body of the stamp132 (e.g., PDMS) but not the polymer domains 144 a, 144 b of theannealed, self-assembled polymer material 142. In some embodiments, asolvent can be used that also swells one but not both of the polymerdomains of the self-assembled polymer material, e.g., the polymer domainthat is subsequently selectively removed (e.g., PMMA lamellae 144 a).After separation and removal of the stamp 132 from the self-assembledpolymer material, the stamp 132 can then be re-used for furthertemplating on another area or substrate bearing a BCP material layer.

The self-assembled polymer material 142 can then be developed toselectively remove one of the polymer domains (e.g., PMMA lamellae 144a) to produce a mask 146 composed of the remaining polymer domain (e.g.,PS lamellae 144 b) with openings 148 in the desired pattern of linesexposing the substrate 112, as shown in FIGS. 53 and 53A. The underlyingsubstrate 112 can then be etched (arrows ↓↓) using the mask 146, asshown in FIGS. 54 and 54A, to form openings 150 to an underlying activearea or element 152. The residual mask 146 (i.e., PS lamellae 144 b, 144b ₁ and PMMA lamella 144 a) can then be removed and the openings 150filled with a material 154, e.g., a metal or conductive alloy such asCu, Al, W, Si, and Ti₃N₄, among others, as shown in FIGS. 55 and 55A toform arrays of parallel conductive lines 154 having a width over a rangeof about 5-50 nm, to the underlying active area, contact, or conductiveline 152. Further processing can be conducted as desired.

In other embodiments, the block copolymer material 116 can becylindrical-phase block copolymer (BCP) on a neutral wetting layer 114(FIG. 34). Referring to FIGS. 56 and 56B, a master template 118″ can beformed with “dots” of a hydrophilic material 122″ (e.g., oxide)surrounded by a hydrophobic material 128″ (e.g., an alkyltrialkoxysilane). The dots of the hydrophilic material 122″ are formedin regions where perpendicular cylinders in the BCP material aredesired, and have a diameter (d) and pitch (p) equal to the L_(o) valueof the cylindrical-phase block copolymer (BCP) material or within about10% or less than the L_(o) value. Other regions (128″) of the mastertemplate 118″ where perpendicular cylinders are not desired arechemically patterned to be hydrophobic.

As shown in FIGS. 57 and 57A, a polymer material (e.g., PDMS) composedof hydrophilic 136 a″ and hydrophobic 136 b″ components (e.g.,molecules) is formed and cured (arrows ↓↓) on the master template 118″.Upon curing, the hydrophilic components 136 a″ of the stamp material134″ align with the hydrophilic dots 122″ and the hydrophobic components136 b″ align with the hydrophobic regions 128″ on the master template118″. The cured stamp 132″ is then removed from the master template 118″and applied to a cylindrical-phase block copolymer material (e.g., 116in FIG. 34), which is annealed while in contact with the stamp (FIGS. 58and 58A (arrow ↓).

Upon annealing, the cylindrical-phase BCP (116), will self-assemble intoperpendicular-oriented cylinders 156″ composed of one polymer block(e.g., PMMA) in response to and aligned with the hydrophilic dots 136 a″on the surface 138″ of the stamp 132″, surrounded by a matrix 158″ ofthe other polymer block (e.g., PS) in response to the hydrophobic areas136 b″ on the stamp surface. In response to areas where the hydrophobicarea 136 b″ has a width (w″) that is greater than or equal to 1.5*L_(o),the block copolymer material will self-assemble to form one or morelines of half-cylinders 156 a″, which are oriented parallel to and incontact with the neutral wetting layer 114″. The number of lines ofhalf-cylinders 156 a″ can vary according to the width (w″), for example,a single line of a parallel half-cylinder will form from a blockcopolymer (L_(o)=50 nm) where the hydrophobic area 136 b″ has a width(w″) of about 70-80 nm. The stamp 132″ is then removed (arrow ↑) fromthe surface of the annealed and self-assembled block copolymer material142″.

As depicted in FIG. 59, the cylinders 156″ (e.g., PMMA block) can thenbe selectively removed to form a mask 146″ composed of cylindricalopenings 148″ within the matrix 158″ of the other polymer block (e.g.,of PS) to expose the base substrate 112″. The substrate 112″ can then beetched using the mask 146″ to form cylindrical openings 150″ (shown inphantom) to active areas 152″ in the substrate 112″. The etched openings150″ can be filled with an appropriate material 154″ to form contacts tothe underlying active areas 152″ (e.g., conductive lines), as depictedin FIGS. 60 and 60A. The substrate can then be additionally processed asneeded.

The present embodiment of the invention of overlying a chemicallypatterned stamp to direct self-assembly of a BCP film eliminates theneed for forming a substrate template pattern, which requires the use ofa patterning technique such as EUV lithography or other sub-lithographicpatterning techniques to physically or chemically pattern the surface ofa substrate, e.g., with chemical stripes (chemical templating), eachstripe being preferentially wetted by the alternate blocks of a blockcopolymer to cause polymer domains to orient themselves above thepreferred stripes and perpendicular to the surface. The presentembodiment of a chemically patterned stamp provides a low cost andre-usable method to provide registered self-assembled block copolymerswith long-range order without the need for patterning a substrate.

The use of a chemically patterned stamp to direct ordering of aself-assembling block copolymer material does not require patterning ofthe substrate to form a topographically varied surface as required bygraphoepitaxial self-assembly, which significantly reduces costs. Also,only an original master template requires patterning usingsub-lithographic tools (e.g., EUV, e-beam, etc.), and at least twolevels of amplification result including the fabrication of multiplestamps from a single master template, and the ability to use each stampmultiple times to direct ordering of BCP materials. As a result, thecost of preparing the master template is significantly amortized. Inaddition, since the stamp is topographically flat, problems of lift-offfrom a self-assembled polymer film are minimized in conjunction with thesurface areas in contact, which provides a significant advantage overnanoimprint lithography. Long-range order and defectivity of aself-assembled block copolymer film is also improved as the stamptemplates and directs the proper order in each region of the film. Bycomparison, graphoepitaxy requires force fields generated fromtopographic features to impose order from a distance.

As depicted in FIG. 61, the present stamp embodiments can be used toform a variety of geometries for integrated circuit layouts 154,including periodic conductive lines 156 and contacts 158, lines withbends 160, isolated lines and contacts, etc., as needed for the circuitdesign. Dies comprising the conductive lines and contacts can beincorporated into a circuit module, device or electronic system,including processor systems.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement that is calculated to achieve the same purpose maybe substituted for the specific embodiments shown. This application isintended to cover any adaptations or variations that operate accordingto the principles of the invention as described. Therefore, it isintended that this invention be limited only by the claims and theequivalents thereof. The disclosures of patents, references andpublications cited in the application are incorporated by referenceherein.

What is claimed is:
 1. A stamp, comprising: a structure having a firstsurface and a second surface, and comprising: transparent regionscomprising a material formulated to transmit ultraviolet radiationtherethrough; and non-transparent regions adjacent the transparentregions; and a polymerizable material directly on surfaces of thetransparent regions and the non-transparent regions defining the firstsurface of the structure.
 2. The stamp of claim 1, wherein thetransparent regions comprise glass, calcium fluoride, diamond, atransparent plastic, or a transparent polymer material.
 3. The stamp ofclaim 1, wherein the non-transparent regions comprise an elastomericpolymer material.
 4. The stamp of claim 1, wherein the transparentregions and the non-transparent regions each extend from the firstsurface to the second surface.
 5. The stamp of claim 1, wherein thepolymerizable material comprises a neutral wetting material.
 6. Thestamp of claim 1, wherein the transparent regions and thenon-transparent regions exhibit substantially the same widths as oneanother.
 7. The stamp of claim 1, wherein the polymerizable materialcomprises a random block copolymer.
 8. The stamp of claim 1, wherein thepolymerizable material comprises PS-r-PMMA.
 9. The stamp of claim 1,wherein the polymerizable material is formulated to be cross-linked uponexposure to at least one of ultraviolet radiation and deep ultravioletradiation.
 10. The stamp of claim 1, wherein the non-transparent regionscomprise poly(dimethylsiloxane).
 11. The stamp of claim 1, wherein thetransparent regions comprise SiO₂.
 12. The stamp of claim 1, wherein thetransparent regions comprise calcium fluoride.
 13. The stamp of claim 1,wherein the transparent regions comprise diamond.
 14. The stamp of claim1, wherein: the transparent regions of the structure comprise quartz,calcium fluoride, or diamond; the non-transparent regions of thestructure comprise poly(dimethylsiloxane); and the polymerizablematerial comprises PS-r-PMMA.
 15. A method of forming a pattern on asubstrate, comprising: forming a stamp comprising: a structurecomprising: transparent regions comprising a material formulated totransmit ultraviolet radiation therethrough; and non-transparent regionsadjacent the transparent regions; and a polymerizable material directlyon surfaces of the transparent regions and the non-transparent regionsof the structure; contacting the substrate with the stamp to apply thepolymerizable material to the substrate; transmitting radiation throughthe transparent regions of the structure to polymerize portions of thepolymerizable material and form a polymeric material comprisingpolymerized portions and non-polymerized portions; and removing thestructure from the polymeric material.
 16. The method of claim 15,further comprising, removing the non-polymerized portions of thepolymeric material relative to the polymerized portions of the polymericmaterial to expose portions of the substrate.
 17. The method of claim16, further comprising: forming a block copolymer material over thepolymerized portions of the polymeric material and the exposed portionsof the substrate; and annealing the block copolymer material to form aself-assembled block copolymer material.
 18. The method of claim 17,further comprising selectively removing one block of the self-assembledblock copolymer material relative to another block of the self-assembledblock copolymer material.